Barium sulfate is used
as a contrast agent to improve the visualization of the gastrointestinal
tract in an x-ray image. In the early days (ca. 1910-1920), there
were a few instances where barium sulfide, which is poisonous, was
administered rather than barium sulfate. Not good. To prevent this from
happening again, various companies marketed barium sulfate strictly for
the x-ray market, often under their own brand names.

A major problem with
barium sulfate is that is is not soluble in water. The best you can do is to keep it in a suspension. If it settles out during an x-ray exam,
the images will be compromised. In addition, there is the possibility that
the accumulated barium sulfate could block constrictions in the GI tract.
In the 1920s, various formulas were developed to keep the barium in
suspension, and one of the first to be marketed was I-X Barium Meal
produced by Industrial X-ray Research Laboratories of St. Louis. So now
you know what "I-X it stays up" means.

Quoting a 1929 advertisement: "I-X Barium Meal really stays in
suspension and actually eliminates constipation caused by taking Barium
Sulphate internally." This advertisement also announces
"an improved package" that is different from the one pictured
above. I assume the one shown here is the older design.

For an informative historical discussion about the use of barium
sulfate see "Roentgen and the New Light - Roentgen's Moment. Part 4:
Of Gastrointestinal Radiology, Bread and Butter; or The Flowering of
Barium Sulfate" by D. Patton. Invest. Radiology 29 (4): 472-479;
1994.